1. Field of the Invention
The present invention relates to a sliding, device, more particularly to the sliding device such as fur use on an artificial ski slope for ski descending practice, and those mounted on the ski, sleigh, skate board.
2. Description of Prior Art
If artificial snow is used on the artificial ski slope, it costs much for producing the artificial snow and installing air conditioners so that the artificial ski slope having an artificial lawn thereon (hereinafter referred to as artificial lawn ski slope) has become a main current for ski descending practice.
The artificial lawn ski slope comprises an artificial lawn layed on the slope. A descending sheet (mounted on the slope (hereinafter referred to as sheet) has the artificial lawn made of flexible or rigid plastic fiber implanted thereon. The people (hereinafter referred to as player) can ski smoothly on the artificial lawn ski slope since the slide and the cushion necessary for descending is obtained between the artificial lawn ski slope and a pair of skis (hereinafter simply referred to as ski).
A sliding surface of a prior art sliding device of such as a ski is formed flat so as to slide on the snow slope or the artificial ski slope provided with a direction restricting groove along the center of the width direction thereof. A prior art sleigh is generally provided with the sliding surface of the same structure set forth above. Prior art skate boards (hereinafter referred to as simply skate board) have rollers corresponding to the wheels, which are supported by shafts provided at the bottom surface thereof so as to rotate forward and backward.
The prior art sliding device formed of conduit shape typically comprises an inclined flat bottom plate, and side plates or frames protruded from the bottom plate at both sides thereof. The player sits on the sliding device and grips the side frames while sliding on the slope.
There has been proposed the sliding device comprising the bottom plate having a plurality of rollers uniformly arranged thereon. This sliding device utilizes a sliding friction generated between the rollers and the slope. The rollers are supported, like beads on an abacus, by a plurality of shafts arranged laterally on the bottom plate or accommodated in a plurality of recessed holes provided at the bottom plate thereof.
However, there are the following problems in the prior art sliding device. Firstly, inasmuch as the ski slides against a sliding friction between the ski and the lawn there produces considerable high frictional heat for thereby melting the lawn whereby the melted lawn is attaChed to the ski. Accordingly, the artificial lawn is soon damaged at the place where frequent descending occurs, and hence the lawn must often be replaced by a new one. Due to melting of the artificial lawn, the descending speed is restrained, differing from on the natural snow slope so that the desired speed can not be obtained.
Secondly, inasmuch as the artificial lawn is liable to reduce the descending speed, the artificial ski slope is sharply inclined to obtain high descending speed which involves damage to the artificial lawn, although the natural snow slope is melted at its surface and provides very low friction between the ski and the thin layer of melted snow so that the player can descend on the natural snow slope at high speed.
In the case of the prior art ski or the sleigh, the player can not slide on the ski without the natural snow on the natural ski slope and it costs much for installing the artificial lawn facilities since the plastic fiber is implanted on the sliding sheet and the thus implanted sliding sheet is worn or melted by the frictional heat generated between the ski and the sliding sheet. Hence, the sleigh and the sliding sheet involve less durability and high cost for maintenance thereof.
On the other hand, in the case of the prior art skate board, if the rollers are simply supported by the shafts, the player feels an inferior cushion which makes the player uncomfortable. When the shafts supporting the rollers are urged by springs for obtaining better cushion, the structure is complicated, and the player is liable to be involved in accidents and feels unbalanced and unstable.
In the case of the sliding device having a flat bottom plate, the hip is heated during descending action due to the frictional heat and the desired speed can not be obtained because of the frictional heat unless the slope is sharply inclined. If the slope is shaply inclined, the danger is increased during the descending action which involves the difficult assurance of safety.
In the case of the prior art sliding device having the rollers provided at the bottom plate (hereinafter referred to as roller type), a considerable high speed can be obtained even on the gentle slope, which assures the safety but there is a likelihood of danger that the rollers are caught in the parts of the wear. Furthermore, since the hip strikes strong against the corner of the roller which permits the player to feel pain at their hips, there is a problem that comfortable descending can not be obtained. Still furthermore, the roller type is difficult to use when the descending surface on the slope is curved relative to the width direction of the slope and both sides of the slope are gradually elevated. Hence, in the roller type, both sides of the slope are elevated stepwise in the an unnatural manner.
More still furthermore, in the roller type, the guiding direction due to the rotation of the roller is restricted by the rotary direction thereby making turns difficult. Hence, the design of a curved and variable course is restricted. Even if the slide is so designed that the player can readily turn on the slope with his own intention, and the slope is wider like the ski slope, it is difficult to turn the sliding direction without applying force to the rollers with might and main. There is a danger of falling down on the slope if the player applies the force on the slide with might and main.